The dbm Calculator & Reference table for 50 Ohms

What is dBm?
A logarithmic ratio with a reference power of P0 = 1.000 milliwatt = 0 dBm.
dBm is defined as power ratio in decibel (dB) referenced to one milliwatt (mW) and the "m" in dBm stands for milliwatt.With the known impedance value you
can convert voltage V to level dBm (power) and vice versa.